SIL: Introduce SILType::hasParameterizedExistential()

Author: slavapestov

include/swift/SIL/SILType.h

@@ -419,6 +419,12 @@ class SILType {
   bool hasLocalArchetype() const {
     return getASTType()->hasLocalArchetype();
   }
+
+  /// Returns true if the referenced type is expressed in terms of one
+  /// or more parameterized protocol types.
+  bool hasParameterizedExistential() const {
+    return getASTType()->hasParameterizedExistential();
+  }
 
   /// Returns the representation used by an existential type. If the concrete
   /// type is provided, this may return a specialized representation kind that